Opposed piston engine



March 13, 1951 MALLORY 2,545,098

OPPOSED PISTON ENGINE Filed Sept. 30, 1949 2 Sheets-Sheet 1 a I, o. i z a! a a JUL INVENTOR. War/a0 Maw/0y A TTOPNEYS' March 13, 1951 MALLORY 2,545,098

OPPOSED PISTON ENGINE Filed Sept. 30, 1949 2 Sheets-Sheet 2 INVENTOR Mario/7 Ma/m y ATTO R N EY Patented Mar. 13, 1951 UNITED STAT-ES -PATENT OFFICE OPPOSED PISTON ENGINE Marion Mallory, Detroit, Mich. Application September 30, 1949, Serial l lo. 118,867

. Claims. 1

This invention relates to the typ of internal combustion engines having a cylinder with two opposed pistons connected to crank shafts geared together so that one shaft rotates twice as fast as the other. My invention consists in constructing an engine of this type so that the power stroke begins with both pistons substantially at inner dead center, and the exhaust port is positioned so that the slow moving piston starts to uncover it at substantially the point where the pistons are the greatest distance apart that they will be during one complete rotation of the slow crank, and a centrally positioned port introduces scavenging air and the charge.

One embodiment of the invention and some permissible variations thereof will be described with reference to the accompanying drawings which form a part of this specification, and in which Fig. 1 is a somewhat diagrammatic longitudinal section of one form of the invention with parts in firing position; Figs. 2, 3 and 4 ar similar views showing the parts respectively at the beginning, mid-point and end of th exhausting period; and Fig. 5 is a diagrammatic view of one form of fuel charger.

In the form of invention shown in the drawings there is a cylinder I with opposed pistons 2 and 3 therein and having a side chamber 4 opening into the cylinder through port 5 between the pistons when both are at inner dead. center. A spark plug '5 is located in chamber d, and a valve l governs the admission of air to chamber 4. The introduction of air is controlled by cam shaft 8, as will be described below. An exhaust port 9 is provided through the cylinder wall where it will be uncovered by piston 3 in the outer portion of its travel.

Pistons 2 and 3 are connected respectively by rods in and i l to cranks i2 and 13 on shafts I4 and I5. These shafts are connected by suitable means, such as gears 16, I! and I8, so that shaft Hi rotates twice to one rotation of shaft l5. Cam

dead center. The exhaust port 9 is so positioned that it begins to open upon further movem nt of the pistons. Thus a relatively long power stroke is obtained. With most internal combustion engines the exhaust must be opened long be fore the movement of the pistons has given the greatest capacity to the cylinder, in order to avoid serious back. pressure against the return movement of the piston. In the described. construcshaft 8 is driven at the same speed as shaft [5 i by any suitable means, such as gears 19 and 20. In the form shown here, cam 22 on shaft '8 operates a stem 23 controlling valve 1.

In Fig. 1, the pistons are both shown in their inner dead center position, at which point the charge may be fired by spark plug 5 in th usual way. It will be noted that the inner ends of the pistons have 'little space between them except where piston 3 is beveled at 24, so that most of the charge is confined in chamber 4.

The fired charge drives the pistons apart as long as they continue to separate. Even after piston 2 reaches its outer dead center and starts back into the cylinder, due to the angles of the cranks, piston 3 moves outward faster than piston 2 moves inward. Exactly how long this continues depends upon the proportions of the cranks and piston rods, but the pistons reach their greatest distance apart at approximately the piston shown in Fig. 2, with piston 2 about 31 past outer tion, the outward movement of piston 3 continues until the outer dead center, the position shown in Fig. 3, is reached, and this tends to counterbalance the pressure on piston 2, so that it is feasible to utilize the full length of the working stroke, or approximately 105 of travel of piston 3 and 211 of travel of piston 2, before the exhaust opens. As will be seen, the exhaust port is open from the position shown in Fig. 2 until the corresponding position is reached, as shown in Fig. 4, so that the exhaust is open for approximately 149 of travel of piston 3 and 298 of travel of piston Z.

scavenging air, introduced at 5, may start to enter as soon as the exhaust is open, but it is preferable to delay it until after the pressure is somewhat lowered by the exhaust. As indicated on the drawings, cam 22 is positioned to open valve 1 upon further movement, but opening could be delayed until it has traveled about 20 beyond the position shown in Fig. 2. By properly relating the cam and contacting valve stem, the timing of valve '1 may be varied if desired, but in the construction shown, valve 1 closes shortly after the exhaust closes, as shown in Fig. 4.

,- If desired, the air admitted through valve 1' may contain the necessary fuel, but the engine is also well adapted for the injection of fuel by a well known injection pump, shown diagram matically at 30 in Fig. 5, where it is shown as being controlled by cam 22 and stem 3|;

The spark plug may be omitted for full Diesel operation, or may be employed in the usual way, or may be operated as a timed electrically heated hot spot, as fully described in my co-pending application for Opposed Piston Engine, filed September 30, 1949, Serial No. 118,868.

It will be seen that practically the entire explosion pressure in this engine is maintained in the cylinder as long as pressure would cause turning power of the cranks, in other words, the exhaust valve does not open as long as any pressure existing in the cylinder has turning power against the cranks. In other types of engines it is necessary to pre-release the exhaust as early as before the crank reaches the end of its power stroke so that the exhaust can escape and lower the cylinder pressure before the piston starts on its exhaust stroke. If the exhaust valve was not opened early in the ordinary engine, the pumping loss would be great, caused by the piston pumping the high pressures out through the exhaust valve.

Another thing: in the ordinary type of engine if the exhaust valve was not opened early, the pressures would be so high at the end of the exhaust stroke and at a time when the piston was starting on its intake stroke that it would be 'diflicult to get in the intake charge due to the cylinder pressure existing when the intake valve opened. In my engine the cylinder pressure on the exhaust stroke is very low and, due to the fact that any exhaust pressures that exist in the cylinder will give turning power to the slow turning crank, it greatly compensates for any pumping losses due to exhausting.

The engine has a very long exhaust stroke and a very long intake stroke, in other words, just consider crank 12 being the power crank of an ordinary engine. On the exhaust stroke in my engine exhaust port 9 opens at position shown in Fig. 2 with crank [2, 31 past its bottom dead center. Exhaust port 9 is open until crank 12 reaches position shown in Fig. 4. That gives 298 time of travel of crank l2 for the exhaust to be moved out through port 9, which greatly reduces the pumping loss inherent in other types of engines. Moreover, the cylinder pressure for exhaust is not released until the power crank I2 is in position shown in Fig. 2. At that time the burning will be practically completed and the cylinder pressures will be very low.

The charging time of the engine is approximately the same as the exhausting time, which is a much longer time than in the ordinary engine, and in addition to this piston 2 doing half the scavenging and half of the charging, that is, forces out half the exhaust and assists in drawing in the charge, makes possible a very low pressure blower or external charger which relieves the engine of additional load where high charging pressures are required.

Thus thorough scavenging and consequent complete combustion is coupled with full utilization of the entire expansion of the effective vol ume between the pistons to form a long working stroke, while still avoiding any serious retarding effect of gas pressure on the pistons during the exhaust period.

Obviously small adjustments of angular relations and exact timing of firing, exhaustand charging may be made, but the best results follow the arrangement and timing substantially as described.

What I claim is:

1. An internal combustion engine comprising 7 a cylinder, opposed piston in the cylinder, mechanical connections between the pistons reciprocatin one of the pistons twice to one reciprocation of the other piston, means for burning a charge between the pistons, said connections positioning both pistons at inner dead center when the charge is fired, an exhaust port at the end of the cylinder in which the glow piston works and positioned at a point where the slow piston starts to uncover it when the fast piston has traveled from firin position to a point past outer dead center to where its speed of inward movement equals the speed of outward movement of the slow piston.

2. An internal combustion engine comprising a cylinder, opposed pistons in the cylinder, mechanical connections between the pistons reciprocating one of the pistons twice to one reciprocation of the other piston, means for burning a charge between the pistons, said connections positioning both pistons at inner dead center when the charge is fired, an exhaust port at the end of the cylinder in which the slow piston works and positioned at a point Where the slow piston starts to uncover it when the fast piston has traveled from firing position to a point approximately 31 past outer dead center.

3. An internal combustion engine comprising a cylinder, opposed pistons in the cylinder, mechanical connections between the pistons reciprocating one of the pistons twice to one reciprocation of the other piston, means for burning a charge between the pistons, said connections positioning both pistons at inner dead center when the charge is fired, an exhaust port at the end of the cylinder in which the slow piston works and positioned at a point where the slow piston starts to uncover it when the fast piston has traveled from firing position to a point approximately 31 past outer dead center, a chargin port midwa longitudinally of the cylinder, and means to introduce air under pressure through the last said port substantially throughout the time during which the exhaust port is open.

4. An internal combustion engine comprising a cylinder, opposed pistons in the cylinder, mechanical connections between the pistons recipro'cating one of the pistons twice to one reciprocation of the other piston, means for burning a charge between the pistons, said connections positioning both pistons at inner dead center when the charge i fired, an exhaust port at the end of the cylinder in which the slow piston works and positioned at a point where the Slow piston starts to uncover it when the fast piston has traveled from firing position to a point approximately 31 past outer dead center, a charging port midway longitudinall of the cylinder, and means to charge the cylinder through said charging port beginning when the slow piston has traveled from 0 to 2% after the exhaust begins to open and continuing after the exhaust is closed.

5. An internal combustion engine comprising a cylinder, opposed pistons in the cylinder, mechanical connections between the pistons reciprocating one of the pistons twice to one recipro cation of the other piston, means for burning a charge between the pistons, said connection positioning both pistons at inner dead center when the charge is fired, an exhaust port at the end of the cylinder in which the slow piston works and positioned at a point where the slow piston starts to uncover it when the fast piston has traveled from firing position to a point approximately 31 past outer dead center, means for introducing air into said cylinder beginning shortly after the exhaust port begins to open, and continuing a longer time after the exhaust closes, and means to introduce liquid fuel just prior to firing.

MARION MALLORY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,031,318 Junkers Feb. 18, 1936 2,473,759 Mallory June 21, 1949 2,486,185 Mallory Oct. 25, 1949 FOREIGN PATENTS Number Country Date 849,614 France 1939 

